Manufacture of homologues of para-aminophenylarsinic acids.



"UNITED STATES PATENT OFFICE.

i WIG BENDA, OF FRANKFORT-QN-THE-MAIN, GERMANY, ASSIGNOR TO FARBWERKE VORM; MEISTER LUCIIT S dz BRUNING, OF HOCHST-ON-THE-MAIN, GERMANY, A CORPO- RATION OF GER-MANY.

MANUFACTURE'OF HOMOLOGUES OF PARA-AMINOPHENYLARSINIC ACIDS.

Specification of Letters Patent.

Patented March 2, 1909.

Application fiIed JuIy 13, 1908. Serial No. 443,383.

I); all whom it may concern; v Be it known that I, Lunwrc BENDA, P11. l,)., a citizen of the Empire of Germany, residing at Frankfort on the Main, Hesse- Nassau, Prussia, Germany, have invented Cir certain new and useful Improvements in the Manufacture of Homologucs of the Para Aminophcnylarsinic Acids, of which the following is a specification.

I have found that by heating with arsenic acid aromatic amins in which the para-p0- sition to the amino group is'occupied by hydrogen, for example orthotoluidin, metatoluidm and paraxylidin, besides colored products resulting from oxidation of the alums, homologues of p-aminophenylarsmic acid are also produced. B choosing suitable conditions a considerablb part of the aromatic amins may even be transformed into the arsinic acids.

The new compounds are white crystallizin'g bodies, readily soluble in hot water, which form with alkalies and alkalicarbonates crystallizin salts; they are difiicultly soluble in alcoho in ether and benzene they are insoluble. By dilute hydrochloric acid they are recipitated from concentrated solutions o the1r alkali salts. When treated with nitrous acid thpyhare transformed into diazo compounds. en heated, they melt at a high temperature and decompose. They can be used for the same purpose and in the same manner as atoxyl and serve moreover as parent materials for manufacturing other coihpounds for medical purposes.

[The procedure for manufacturing the new compounds may for instance be as follows:

- In a stirring vessel which is laced in an oil bath, 90 kg. of o-toluidin are eated. .When

the internal temperature has risento 24 kg. of 1 owdered arsenic 'acid are graduallyadde while stirring and further heat ing. The heating is continued while con stantly stirring in such a manner that after about one hour the internal temperature amounts to 165-168 then watcrand some toluidin is distilling off; the temperature of the oil bath is further increased and kept for one hour so that the internal temperature amounts to 185-1909 N ow the mixture is allowed to cool and at abou" 150 the contents ofthe vessel'is ressed into cold water; is neutralize with caustic soda lye and made strongly alkaline by milk of lime whereupon the excess of toluidin is distilled oil 1 ith steam. The remaining liquid is saturated with common salt and filtered ofl after 24 hours. To the filtrate so much of concentrated hydrochloric acid is added that nicthylorangc becomes slightly reddened; there will then separate at first a byproduct in a resinous form. Solution separated from this resin is allowed to stand for 20 hours or for a longer time, whereupon the amino ortho-tolylarslnic acid crystallizes. in order to urify it, the raw product is dissolved in a 'ttle hot water with the quantity of caustic. soda lye necessary for exact neutralization, and the solution which may eventually be treated with some animal charcoal-is mixed with a 1 times its volume of alcohol.

The sodiumsalt turns out crystalline; it is very readil soluble in water, rather difiicultly solu Is in alcohol, but insoluble in benzene and ether. From the concentrated aqueous solution of the sodium salt, the free ammo-ortho-tolylarsinic acid may be eliminated by the addition of hydrochloric acid. It crystallizes from hot water in the form of needles which melt at ISM-195; they are difiicultly soluble in alcohol, insoluble in benzene and ether, readily soluble in an excess. of dilute acids and in alkalies and alkalicarbonates. The amino-ortho-tolylarsinic acid can be diazotized and combined to form dyestuffs which resemble the corresponding suifanilic acid dyestuffs The constitution of the aminotolylarsinic acid obtainable from orthotoluidin corresponds to the formula:

C HJCH :NH, :ASO (OH)2 1 :2 i5) and its formation may be' explained by the equation:

0.114011 iun nso r-r n o. If metatoluidin and paraxylidin are used instead of the ortho-toluidin, the aminometatolylarsinicacid I c.,H,, oH,,=NH Aso(oH 1 =3 sj and the amino-pardxylylarsinic acid C 11 (CH,:CH, :NH, :AsO (OH); 1 :4: 2 :5)

:ire produced which are very similar to the amino ortho tolylarsinic acid and which melt at 180 and 215 respectively.

Claims.

1. The process of manufacturing the homologues ol" psriraininoplienylarsinic acid,

which consists in heating with arsenic acidthe homologues of the enilin in which the para position to the amino group is occupied by hydrogen.

2. As new products, the homologues of amino-phenylarsinic acid, the constitution of which corresponds to the general formula: C 11 ,,(CH ),,:NH :AsO(()H) and which contain the group As() l in para position to the amino group, being white crystalline compounds which are readily soluble in hot water, more difhcultly soluble in cold water, difiicultly soluble in alcohol, insoluble in benzene and ether, melting at from 180 to 215 0., forming with alkalies, alkali-carbonetes, or an excess of dilute mineral acids,

readily soluble salts, and being diazotized by nitrous acid.

3. As a new product, amino-ortho-tolylresponds to the formula: ",1.

C H tcH zNH :AsO (OH) 1 :2 :5),

being a white compound, crystallizing in the form of needles which are readil soluble in hot water, more diflicultly solu le in cold water, difiicultly soluble in alcohol, insoluble in benzene and ether, melting at 194-195" forming with alkalies, alkelicerbonetes, of an excess of dilute mineral acids, readily soluble salts, and beingdiazotized by nitrous acid:

In testimony whereof, I affix my signature in presence of two witnesses.

, LUDWIG BENDA.

Witnesses: I v

CARL GRUND, v JEAN GRUND.

25 arsinic acid, the constitution of which cor- 

